The invention relates to a retroreflecting optical communication system which includes apparatus for modulating a laser beam at a point spaced from the source of the beam and to reflect the modulated beam toward the source of the beam to transmit in the direction of the source signals imposed on the beam at the retroreflector.
Related subject matter is disclosed and claimed in U.S. Pat. No. 3,943,357 granted Mar. 9, 1976 entitled Remote Controlled Vehicle Systems, W. H. Culver.
The modulation means of the system utilizes a modification of the principles of Stark effect modulation described in an article entitled "Stark Effects in C.sup.13 H.sub.3 F: Passive Q Switching of the CO.sub.2 Laser Using C.sup.13 Enriched Methyl Fluorides, by Eric Weitz and George Flynn in Journal of Applied Physics Vol. 42 No. 12 (Nov. 1971) pages 5187-5190, and in earlier publications cited in the article.